Many chemical compounds needed for various industries have for many years been derived from the petrochemical industry. However, due to increases in the price of crude oil and a general awareness of replacing petrochemicals with renewable resources there has been and still is a wish to base the production of chemical compounds on renewable resources.
5-hydroxymethylfurfural (HMF) is an example of such a compound because it is derived from dehydration of sugars making it derivable from renewable biomass resources. HMF can for example be converted to 2,5-dimethylfuran by hydrogenolysis of C—O bonds over a copper-ruthenium (CuRu) catalyst (Roman-Leshkov Y et al., Nature, 2007, 447 (7147), 982-U5), which is a liquid biofuel or to 2,5-furandicarboxylic acid by oxidation (Boisen A et al., Chemical Engineering Research and Design, 2009, 87(9), 1318-1327). The latter compound, 2,5-furandicarboxylic acid, can be used as a replacement of terephthalic acid in the production of polyesters such as polyethyleneterephthalate (PET) and polybutyleneterephthalate (PBT).
US 2008/0033188 discloses a catalytic process for converting sugars to furan derivatives, e.g. 5-hydroxymethylfurfural, using a biphasic reactor containing a reactive aqueous phase and an organic extracting phase.
Román-Leshkov Y and Dumesic J A, 2009, Top Catal, 52; 297-303 discloses similar subject-matter as US 2008/0033188.
US 2009/0030215 discloses a method of producing HMF by mixing or agitating an aqueous solution of fructose and inorganic acid catalyst with a water immiscible organic solvent to form an emulsion of the aqueous and organic phases.
U.S. Pat. No. 7,317,116 discloses an method for utilizing an industrially convenient fructose source for a dehydration reaction converting a carbohydrate to a furan derivative.
Huang R et al., 2010, Chem. Comm., 46, 1115-1117 discloses integrating enzymatic and acid catalysis to convert glucose into 5-hydroxymethylfurfural.
In the industrial manufacture of high-fructose corn syrup, glucose is often converted into fructose by a process catalyzed by the enzyme xylose isomerase (E.C. 5.3.1.5) which for these reasons is usually called a “glucose isomerase”.
Glucose can be isomerized to fructose in a reversible reaction. Under industrial conditions, the equilibrium is close to 50% fructose. To avoid excessive reaction times, the conversion is normally stopped at a yield of about 45% fructose.
Glucose isomerase is one of the relatively few enzymes that are used industrially in an immobilized form. One reason for immobilization is to minimize the reaction time in order to prevent degradation of fructose to organic acids and carbonyl compounds that inactivate the enzyme.
The substrate to the GI-columns is highly purified to avoid clogging of the bed and destabilization of the enzyme. The recommended conductivity is <50 μS/cm.
A description of the most commonly used glucose isomerases is given in table 1 below. The description is based on literature and information from the manufactures and do not necessarily have to be a description of the exact methods used.
TABLE 1ImmobilizationManufacturerTrade nameEnzyme sourcemethodNovozymesSweetzyme ITS. murinusCrosslinking of cellA/Smaterial withglutaraldehyde,extrudedGenencorGENSWEETS. rubigonosusThe enzyme is crossInternationallinked with or withoutcellular debrisusing PEI(polyethylene imine)and glutaraldehyde.Granular particles areformed by extrusion/marumerization.GodoAGI-S-600S. griseofuseusChitosan-treatedShuseiglutaraldehydecrosslinked cells,granulated.
Another way of producing fructose is by hydrolysis of sucrose to obtain a composition comprising glucose and fructose in a 50:50 ratio.
A further way of producing fructose is by catalytic conversion of mannose with mannose isomerase to fructose.